* {
margin: 0;
padding: 0;
}
body {
background-color: black;
}
a{
    text-decoration: none;
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%,-50%);
    font-size: 24px;
    background:linear-gradient(90deg ,  #2ba0e4 ,#c58040 , #14d83f, #a666e2 ) ;
    background-size: 400%;
    width: 400px;
    height: 100px;
    line-height: 100px;
    text-align: center;
    text-transform: uppercase;
    border-radius: 50px;
    color: #fff;
    z-index: 1;
}
a::before{
    content: '';
    position: absolute;
    left: -5px;
    right:-5px;
    top: -5px;
    bottom: -5px;
    background:linear-gradient(90deg ,  #2ba0e4 ,#c58040 , #14d83f, #28c49d ) ;
    background-size: 400%;
    border-radius: 50px;
    filter: blur(20px);
    z-index: -1;
}
a:hover::before{
    animation: sun 6s infinite;
}
a:hover{
    animation: sun 6s infinite;
}
@keyframes sun{
    100%{

        background-position: -400% 0;

    }
}